Telephone system



Nov. 22, 1938.

C. E. LOMAX ET AL TELEPHONE SYSTEM Filed May 1'7, 1937 3 Sheets-Sheet 1' m QE m E m qw a Q 2 q q 8 mm 3 8 m m 0 T T A 3 Sheets-Sheet 2 TELEPHONE SYSTEM Filed May 17, 1937 C. E. LOMAX ET AL mot wmN wot Nov. 22, 1938.

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Nov. 22, 1938. c. E. LOMAX ET AL TELEPHONE SYSTEM Filed May 17, 1937 s Sheets-Sheet 5 INVENTOR3. CLARENCE E. LOMAX BY JOHN H. V055 ATTORNEYS Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Application May 17, 1937, Serial No. 142,988

31 Claims.

The present invention relates to signalling systems and more particularly to automatic switching units for use in setting up connections between the various lines or an automatic telephone system.

It is well known that the method by which a connection is established from one line of an automatic telephone system to any desired second line in the system consists of routing a connection by way of automatically operating traific concentration switches and one or more impulse responsive, numerical switches which operate automatically to select the desired line and to establish a connection thereto. Various types of numerical switches for performing the functions noted are known to the art. These switches, irrespective of the type used, are, according to present practice, invariably arranged in groups, the corresponding bank contacts or conductors of the switches of each group being multipled to each other, whereby each switch of each group of switches has access to all of the lines terminating at each of the group of switches. The size of the multiple carried between the bank contacts of the switches comprising any particular group obviously depends upon the number of lines to which the particular group of switches has access. From the standpoint of economy of construction and installation, it is desirable to maintain the size of these multiplies as small as possible. When, however, the size of a multiple is reduced,the number of numerical switches required to serve a given number of subscribers lines is necessarily increased with a corresponding increase in the cost of the apparatus involved. In the past, therefore, the particular arrangement of any given system has been dictated, to a large extent, by the relative cost as determined by the two factors noted. In any case, it is desirable to eliminate bank contact switch multiples where this can be done without unduly increasing the amount of ap paratus involved.

It is an object of the present invention, therefore, to provide .in a signalling system an automatic switching unit embodying a plurality of automatic switches and which is of simple, economical and rugged construction, is faithful in operation, and is devoid of any multiples of the form just described.

In general, the object as set forth above is attained in accordance with the present invention by providing an automatic switching unit having embodied in one unitary structure a plurality of automatic switches. As described in detail hereinafter, the unit structurally comprises a bank of bare or uninsulated conductors which serve both as multiple conductors between the switches of the unit and as wiper contacts for the wipers of the individual switches. These. conductors are arranged in groups, each of which includes a number of smaller groups, and are disposed in the same plane in substantially parallel relation, with substantially the same spacing between the conductors of each smaller group and substantially the same spacing between the adjacent conductors of each adjacent pair of smaller groups. With this arrangement, the individual conductors of the lines outgoing from the unit may be terminated at the corresponding conductors of the various smaller groups and, thus, the corresponding con= clusters of the smaller groups of each group of conductors form conductor sets adapted to be connected to the outgoing lines. In order selectively to connect the lines incoming to the unit to the various conductor sets, thereby to establish line testing and conversational circuits, there are provided groups of wipers, each group being included in one switch of the unit and including sets of wipers associated with the con ductors comprising the conductor sets of the different groups of conductors. Each group of wipers is carried by a spring biased carriage member extending transversely with respect to the bank conductors, which members, in combination with associated stepping magnets and ratchet and pawl mechanisms, comprise means individually associated with the group wipers carried respectively thereby, for translating the wipers to a number of predetermined positions individually corresponding to a particular conductor set in each group of conductors. The wipers of each set are so arranged that, when translated to any one of the predetermined positions, individual ones thereof stand opposite individual ones of the condctors in the conductor sets corresponding to the one position. It is by this arrangement that a particular group of outgoing lines or a particular line in a selected group is selected. Following the translation of any wiper group, the wipers thereof are moved into engagement with the opposed conductors by means comprising a cut-in magnet having an armature adapted to rotate the member upon which the translated wipers are carried. Each such member is adapted to be locked in its translated and rotated position by means comprising a normally de-energized release magnet,- which magnet, upon being energized, operates to permit the spring biased carriage member to restore the wipers carried thereby to their respectlve normal positions. Positioned in the path of each wiper of each group is a common bus bar extending transversely with respect to the smaller group of conductors with which the corresponding wiper is associated so that, when the wipers are rotated, they not only engage the respective oppositely disposed bank conductors, but also the associated bus bars.

Operating in conjunction with the abovedescribed mechanisms and included in the unit are a n urality of stepping switches of the minor type, individual ones of which are associated with the individual groups or" wipers and comprise means for selecting a particular group of bank conductor sets, or a particular conductor set in a selected group. The method of control of the s itching unit and the manner of connecting the l "he provided for performing the control funcpend upon whether the unit is to be eman intermediate or final selecting capacity. In the first instance, impulse responsive means are included in the control means for each on, which operates to cause the wipers of the .ch mechanism included in the switch to perthe line group selecting function, following h are automatically conditioned to cause the associated minor switch automatically to operate to select a particular idle line in the selected group or" lines. If, on the other hand, the unit is to be used as an instrumentality for selecting particular called line in a group of lines, either the minor switch included in a seized switch or the wipers of the switching mechanism thereof may be arranged to perform the group selection, following which the other thereof performs the unit selection. Irrespective of the arrangement, however, both the actuating means for the wipers and the actuating means for the minor switch are under the control of impulse responsive means associated therewith when the switches of the unit are used in a final selecting capacity.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings, in which Figures 1 and 2 illustrate the structural features of the switching mechanisms embodied in an automatic switching unit constructed and arranged in accordance with the present invention; Fig. 3 is a detail view illustrating one of the wipers embodied in the mechanism shown in Figs. 1 and 2; Fig. 4 illustrates the details of one of the cut-in magnets shown in Figs. 1 and 2; and Figs. 5 and 6 illustrate a complete telephone system including automatic switching units of the form shown in Figs. 1 and 2, employed both as the intermediate and final selector switches.

Referring now more particularly to Figs. 1 and 2 of the drawings, the improved switching mechanism there shown comprises a bank of bare or uninsulated conductors arranged in groups, two such groups being indicated at I0 and H. Each of these groups comprises three smaller subgroups, those for the group 10 being indicated at l2, l3 and i4, and those for the group H at [5, i8 and H. As best shown in Fig. 1, all of these conductors are disposed in the same plane in substantially parallel relation. Substantially the same spacing between the conductors of each of the small groups l2, l3 and H and I5, I8 and I1, is maintained. Similarly, substantially the same spacing is maintained between the adjacent conductors of the adjacent smaller groups of conductors. Any suitable means, not shown, may be used for fixedly mounting the conduc tors of the groups noted, so long as the abovedescribed relations between the various conductors are preserved. In the arrangement described, the corresponding conductors of each of the subgroups in any particular group comprise a conductor set at which may be terminated one of the lines outgoing from the switching unit.

Thus, the respective first conductors i2, i3 and H or the smaller groups 12, I3 and it comprise a conductor set 18 which may be connected to one outgoing line. Similarly, the respective first conductors i5, i5 and ll of the smaller groups l5, l6 and il' in the group H comprise a second set which may be connected to a second outgoing line. The respective second, third, fourth and fifth to tenth conductors of each of the smaller groups 12, and i4 included in the group l8 similarly comprise additional conductor sets, each of which is adapted to be connected to an outgoing line.

Extending transversely with respect to the various conductors of the conductor bank are carriage members, two of which are shown at 20 and 2?), upon each of which is mounted a group of double ended wipers, those carried by the member 2Q being individually indicated at 21, 22, 25, 24, 25, 2?: and The carraige members are, in turn, mounted for translatory and rotary movement on a mounting frame 28 comprising side members 29 and which extend substantially the full length of the conductors included in the conductor bank. It will be understood that the carriage members 20 and 20 extend through openings provided in the frame side members 29 and 30 and are slidable therethrough. Each of the enumerated wipers is insulated from the carriage member upon which it is mounted and is associated with one of the smaller groups of bank conductors. Thus, the wiper 2| is associated with the bank conductors comprising the sub-group i2, the wiper 22 with the conductors of the subgroup l3, and the wiper 23 with the conductors of the sub-group H. Normally, each of these wipers stands in a position slightly offset with respect to the first conductor of the associated sub-group, so that, when the carriage member upon which it is mounted is stepped one step to the right, it stands opposite the first conductor in the associated sub-group. It will be noted that this normal position of the wipers is fixed by the left-end surface of an enlarged ratchet element 34 which abuts the adjacent right-hand surface of the frame member 30. It will further be noted that the wipers comprising each group are so spaced along the carriage member upon which they are mounted that, when translated to any predetermined oil-normal position to the right, they stand opposite the corresponding conductors of their respective associated sub-groups. Thus, if the wipers 2| to 21, inclusive, are stepped three steps to the right, the wiper 2| will stand opposite the third bank conductor in its associated sub-group l2, the wiper 22 will stand opposite the third bank conductor in its associated sub-group l3, the wiper 23 will stand opposite the third bank conductor in its associated subgroup etc. It follows, therefore, that each three adjacent wipers included in the same group of wipers and associated with the three subgroups of a group of bank conductors constitute a wiper set which is associated with the conductors comprising the conductor sets of the corresponding group of conductors.

In order to translate the wipers to a desired position such that they stand opposite the conductors of a particular group of conductor sets, there is associated with each of the carriage members actuating means comprising a motor magnet and a ratchet and pawl mechanism. This actuating means for the carriage member 20 comprises a magnet 3| having a spring biased armature 32 carrying, at its lower end, a spring biased pawl 33 which is adapted to engage with the teeth of the ratchet element 34 carried by the right extremity of the carriage member 20. This actuating means is arranged to translate the carriage member 20 and the wipers 2i to 21, inclusive, carried thereby, step-by-step to the right to any desired predetermined off-normal position. Resisting such movement is a biasing spring 35 enclosing the left extremity of the member 20. During such translatory movement and as shown in Fig. 3, all of the wipers carried by the member 20 occupy a position relative to the bank conductors such that no engagement occurs therebetween. In order to cause all of the wipers carried by the member 20 to be rotated in a counterclockwise direction to bring the same into contact with the respective conductors which they oppose following the positioning of the wipers in a particular off-normal position, there is provided means comprising the cut-in magnet 36. As shown in Fig. 4, this magnet 36 includes an armature 31 having a projection 38 which rides in a slot 39 provided in the ratchet element 34 during the translatory movement of the carriage member 20 and serves to rotate the member 20 when the magnet is energized. The member 20 is rotated against the bias provided by the spring 35, this spring being fixedly secured at one end to the side member 23 of the frame 28 and at the other end to the left extremity of the carriage member 20.

For the purpose of maintaining the wipers carried by the member 20 in contact with any selected conductor set, there is provided a release magnet 40 comprising a pivoted armature 4| having a projecting arm 42 which is adapted to engage the straight sides of the teeth out in the ratchet member 34 and includes a small projection, not shown, which enters the slot 39 during the rotation of the member 20 by the cut-in magnet 36. When this magnet 40 is energized, the arm 42 is completely disengaged from the ratchet element 34, permitting the carriage member 20 to restore the wipers carried thereby to their respective normal positions. It will be understood that the means associated with each of the other carriage members for imparting translatory and rotational movement thereto and for holding the same in an operated offnormal position are exactly the same as that shown and described above in association with the member 20.

In the arrangement shown, each of the lines incoming to the switching unit comprises two line conductors and a test conductor, and, as will be pointed out in detail hereinafter, terminates at the wipers of a stepping switch having its bank contact sets connected to sets of bus bars. This switch, indicated diagrammatically at 52, for the group of bus bar sets associated with the wipers carried by the'carriage member 20, is of the minor type and is arranged to perform the line group selecting function or line unit selecting function, depending upon how the selector switch in which it is included is to be used. Similar step,-

ping switches are provided in association with each of the other groups of bus bars incorporated in the switching unit. Positioned in the path of the wipers of each group of wipers during the rotational movement thereof are the bus bars which act as wiper contacts and as stops to limit the rotational movement of the wipers. Individual ones of these bus bars are positioned opposite and extend transversely with respect to each of the various bank conductor sub-groups. The bus bars positioned opposite the respective subgroups l2, l3 and H are indicated at 43, 44 and 45, respectively, and those positioned opposite the sub-groups l5, l6 and I! are indicated at 41, 48 and 49, respectively. These bars may be supported from the frame 28 in any desired manner, and each thereof is arranged so that, irrespective of which off-normal position its associated wiper is translated to, it will be engaged by the wiper when the latter element is sequentially translated androtated by the magnets 3| and 36. It will be seen that the bus bars 43, 44 and 45 comprise a set 50 by way of which a connection may be established from the associated particular stepping switch 52 to any one of a group of ten outgoing lines, these lines being terminated at the ten conductor sets making up the three subgroups l2, l3 and I4. Similarly, the bars 41, 48 and 43 comprise a set 5| through which the same stepping switch has access to the group of ten lines terminating at the subgroups of bank conductors I5, l6, and I1. As will be pointed out in greater detail hereinafter, each ofthe stepping switches embodied in the switching unit performs a line group selecting or a line unit selecting function.

In the operation of the automatic switch including the above-described switching mechanism and the minor switch 52, the motor magnet M is first energized in accordance with a series of impulses received at the switch and, in cooperation with its associated ratchet and pawl mechanism, steps the member 20 to the right to a position corresponding to the impulses of the received series. By this stepping operation, a particular conductor set in each of the groups of bank conductors is selected. Thereafter and when the cut-in magnet 36 is energized, the wipers carried by the member 20 are rotated so that each thereof engages the conductor and bus bar standing oppositely thereof. Thus, a group of lines outgoing from the switching unit to a selected group of subscribers lines or a selected group of final selector switches are connected by way of the bus bars 43, 44, 45, etc., to the banlc contacts of the stepping switch 52. Following the line group selection, the stepping switch 52 operates to select a particular line in the selected group, the manner of its operation depending upon whether the automatic switch in which it is embodied is to be used in an intermediate or final selecting capacity. If the former, the switch 52 automatically operates, immediately following the line group selection, to select a line leading to an idle switch in the selected group, whereas, if used in a final selecting capacity, it operates step-by-step in accordance with a series of received impulses until a particular called line in the selected group of lines is selected. In the last-mentioned case, either the minor switch 52 or the switching mechanism described may be used to perform the line group selecting function, the line unit selection being assigned to the one of these two elements not assigned to perform the line group selection. From the foregoing description it will be understood that the number of groups of bank conductors in the switching unit and the number of conductors in each subgroup will depend upon the number of lines to which'the switching unit is to have access. For example, if the switch unit is designed to establish connections to selected ones of one hundred outgoing lines, ten groups of bank conductors each including three subgroups of ten conductors each will be required.

Although in the above description the outgoing lines terminating at the bank conductors of the switching unithave been regarded as being arranged ingroups corresponding tothe groups of bank conductors ll, I0, 'etc., a slightly different viewpoint of the bank conductor grouping, which yields the same results as regards the line selection, is possible. Thus, with the carriage member moved to any oil-normal position, such for example, as the first, the various wipersof the wiper sets carried thereby stand opposite the bank conductors forming conductor sets leading to the lines of a groupof'outgoing lines. Where,

. as in the case assumed above, ten wiper sets are carried by each carriage member, the oil-normally positioned wipers stand opposite ,bank conductors leading to ten outgoing lines. This constitutes the line group selection. Hence, the operation of the minor switch I! to a selected off-normal position to select a particular wiper set, such for example, as the set II, 22, 23, in the group of wipers mounted'on the member 20 constitutes the line unit selection or, in other words, the selection of a particular line in a selected group of lines.

It is pointed out that the arrangement described above, wherein the corresponding conductors of the sub-groups in each group 'comprise conductor sets connected to the different lines, renders the stepping method of actuating the carriage membei's feasible and results in a decided conservation'in the space required for a unit of a given size. Thus, by this arrangement, the carriage member 20 need only be translated the distance d during each step, whereas if the three conductors of eachj line were terminated at three adjacent or consecutive bank conductors, the carriage member 10 :wduld necessarily have to be translated the distance e, or three times the distance d, in order to move the wipers from one oil-normal position to the next succeeding off-normal position.

Referring now more particularly to Figs. 5

and s of the drawings, there is illustrated a telephone system where'in automatic switching units of the form just described are used as the impulse responsive intermediate and final selecting units. In general, the system comprises a plurality of telephones or subscribers substations, two of which are shown at A and 13, adapted to be interconnected by means including their respective associated subscribers lines I00 and I10 and switch trains including the aforementioned intermediate and final selector units. These switch trains, when established, may individually comprise the usual line switch associated with each subscriber's line, an intermediate selector switch accessible to the line switch associated with the calling subscribers line and a final selector or connector switch accessible to the operated intermediate selector switch and having mtem.

bank conductors in which the called subscriber's line terminates. Thus, in the system shown, the line Ill terminates at a line switch I03, which switch has access to a group of selector switches which may collectively comprise one of the switching units described above, one of these switches being indicated generally at Ill. The latter switch, in turn, has access to groups of final selector or connector switches, the individual groups of which may comprise one of the switching units described above. Thus, the selector switch I04 has access to connector switches, one of which is indicated generally at Ill, at the bank conductors of which the subscriber's line Ill terminates. It is well known that by this general arrangement any subscriber may, by proper manipulation of the impulsing device at his substation, establish a connection between his line and any other idle subscriber's line in Each of the line switches included in the systern, such, for example, as the, line switch I03, may be of any desired. commercial construction although preferably is of the well-known rotary type having three sets of bank contacts, wipers corresponding to the three sets, a ratchet and pawl mechanism for driving the wipers, an operating magnet for actuating the ratchet and pawl mechsnism, and control means whereby the operating magnet is energized to operate buzzer fashion when a call is initiated on the line associated with the corresponding line switch and is de-energisedwhen the wipers are rotated into engagement with a set of contacts corresponding to the first idle intermediate selector switch available.

Neglecting for the present the details of the intermediate and final selector switches I04 and Ill, respectively, and the control means respectively included therein, the system as briefly described above is entirely conventional in form and its operation is well understood in the art. In brief, when a subscriber, such, for example, as the subscriber at the telephone A, initiates a call over the line I00 to a second subscriber's telephone, such, for example, as the telephone B, by lifting his receiver from its hook, the line switch Ill associated with the calling subscriber's line operates to select an idle intermediate selector switch and to condition the same to be responsive to impulses transmitted from the impulsing device at the telephone A. As noted above, each of the intermediate selector switches has access to one or more final selector switches at which any subscriber's line of the system terminates. Thus, if the intermediate selector switch I04 is seized by the line switch I03, it operates, in the manner described hereinafter, in response to the dialing of the first digit at the substation A to select a group of trunk lines extending to the final selector switches at which the called line I10 terminates. Following this, the seized intermediate selector switch I04 automatically selects a trunk line leading to an idle final selector switch in the selected group of switches and connects the calling subscriber's line I00 through to seize this idle final selector switch. Thereafter and in response to the dialing of the second digit, the seized final selector switch selects the group of lines in which the called subscribers line is included. With the switch train in this condition, and when the final or third digit is dialed, the seized final selector switch selects the particular'called line in the selected group of lines and, if this line is idle,

establishes a connection between the calling and called lines when the called telephone B is answered.

The system conventionally includes means whereby ringing current and ring-back tone current are automatically transmitted, respectively,

to the substations of the called and calling parties in case the called line is idle and upon the final selector switch seizing the called line. Also, in accordance with conventional practice, means are provided whereby, in the event the called line is found busy, the calling line is not connected thereto and busy tone current is transmitted back over the established loop to the calling party to indicate the busy condition of the called line. As will be pointed out in detail hereinafter, the arrangement is such that the switch train utilized in establishing the connection is released only when the connection is cleared out at the calling party's substation, the entire switch train being held operated when the called party is the first to hang p. I Each of the groups of intermediate and final selector switches preferably embodies the features of the improved automatic switching unit illustrated in Figs. 1 to 4, inclusive, although it is noted that the system may only partially comprise switching units of this form, the remaining automatic switches being of any welLknown step-by-step type wherein impulse responsive means are utilized to control the operation thereof. The selector switches I04 and I05 are, however, of the exact form embodied in the switching units described above. The switch I04 has access over one hundred outgoing trunk lines, one of which is shown at I3I, to each of one hundred final selector switches and, similarly, each of the final selector switches has access to one hundred subscribers lines terminating at the bank conductors of the various switching units. In view of the previous description, it will be understood that the switching mechanism included within the rectangle I30 comprises a portion of the elements associated with a carriage member I20 corresponding to the carriage member 20, of the mechanism shown in Figs. 1 and 2. It will further be apparent that the trunk conductors indicated at I26 terminate at one set of bank conductors and, similarly, that the trunk conductors I32, I33 and I34 comprising the line I3I terminate at a second set of bank conductors in the same group as the bank conductors to which the trunk conductors of the line I26 extend. The wiper set I23, I24 and I25 and the associated bus bar set I20, I2I and I22 comprise, respectively, single sets of groups of ten similar sets associated with the carriage member I20. The actuating means for this member comprises the motor magnet 285, the cut-in magnet 295 and the release magnet 215. Off-normal springs 243, 246, 241 and 248 are associated with this carriage member for establishing and interrupting control circuits in the manner described in detail hereinafter. Each of the bus bars of the ten bus bar sets in the switch mechanism I30 is connected to a contact in the contact bank of a minor switch IIO. Thus, the bus bar I20 is connected over a conductor I I1 to the fifth contact of the upper level of contacts III, the bus bar PM is connected to the fifth contact of the contact level I I2, and the bus bar I22 is connected by a conductor H9 to the fifth contact of the level II3. These fifth contacts correspond to one predetermined off-normal position of the switch H and the remaining bus bar sets correspond, respectively, to nine of the remaining off-normal positions of the switch H0. The minor switch H0 is of the well-known homing type including wipers having a normal position and operable to a plurality of off-normal positions. This switch includes wipers H4, H and H6, associated with the contact sets III, H2 and H3, respectively, which wipers are connected to the conductors of the trunk line incoming to the switch I04, are movable to eleven off-normal positions, and are spring-biased to their respective normal positions. The actuating and control means for this stepping switch comprises a motor magnet 255, a release magnet 265, and off-normal springs 231, 239, 244 and 245. As will be pointed out in detail hereinafter, the outgoing line group selection of the switch I04 is accomplished by the switching mechanism I30, following which the selection of an idle final selector switch in the selected group of final selector switches is accomplished through the automatic operation of the minor switch H0. To assist in obtaining this form of operation, the control means embodied in the switch includes, in addition to the off-normal springs noted, control relays 200, 220, 230 and 240, and their control and controlled circuits. Although described more particularly hereinafter, it is pointed out here that the off-normal springs 246 and 241 are closed and the springs 243 are opened when the carriage I20 is stepped to its first off-normal position, the spring 248 is operated to its off-normal position when the carriage I20 is rotated by the magnet 295, the springs 245 are opened when the wipers of the switch IIO are stepped to their respective first off-normal positions, and the springs 231 and 244 are closed and the springs 239 opened when the wipers of the switch II 0 are stepped to their respective eleventh off-normal positions.

The final selector or connector switch I05, like the intermediate selector switch I04, has embodied therein a minor switch I50 01 the wellknown homing type having ten off-normal positions and a switching mechanism I65, the latter switching mechanism comprising the group of wipers carried by a carriage member I15 and having associated therewith a group of bus bars including the set I18, I19 and I80. This carriage member is adapted to be translated and then rotated in the manner described previously by means comprising a motor magnet 390 and a cut-in magnet 392 and is arranged to be held in any off-normal position to which it has been operated by a release magnet 39I. Off-normal springs 393, 394 and 395 are provided in association with the carriage member I15 which are electrically incorporated in the control circuits of the switch I05. As pointed out in greater de-' tail hereinafter, the oil-normal springs 396 are closed and the springs 391 are opened when the minor switch I50 steps its wipers to their respective first off-normal positions, the off-normal springs 393 and 395 are closed when the carriage I15 is stepped to its first off-normal position, and the off-normal springs 394 are opened when the cut-in magnet 392 is energized to rotate the carriage I15. Each of the bus bar sets is connected to one set of contacts included in the contact sets I5I, I52 and I53 of the minor switch I50. The wipers I54, I55 and I56 associated, respectively, with the contact sets I5I, I52 and I53 and connected to the line incoming to the switch I05, are arranged to be actuated from their respective normal positions to selected off-normal positions by a motor magnet 338, and to, be held in any off-normal position I to which it has been operated by a release magnet 380. This minor switch I 00 conventionally comprises ofi-normal springs 300 for controlling the operation of the release magnet 309. As pointed out in greater detail hereinafter, when the switch I05 is seized, outgoing line group selection is accomplished by the minor switch I50,"

following which the line unit selection, or the selection of a particular line in the selected group, is accomplished by the switching mechanism I00. The actuating means for the minor switch I00 and the switching mechanism I are under the control of impulse responsive means comprising the line relay 300 and, in order to obtain the sequential group and unit selection noted, together with the other functions normally performed by a final selector switch, additional control means comprising relays 3I0, 320, 340, 300, 360, 310, 300, and their control and controlled circuits are provided. The switch I 00 also has associated therewith ringing apparatus, not shown, for transmitting ringing current to a called subscribers line and ring-back tone current to a calling subscriber's line, and a generator, not shown, for transmitting busy tone current to a calling subscriber's line, in the event a particular called line is found busy.

Considering now the detailed operation of the intermediate selector switch I 04 during the abovedescribed sequence of operations, when this switch is seized by the line switch I03, a circuit is completed for energizing the line relay 220, which circuit extends from ground at the lower winding of the relay by way oi this winding, the conductor I38, the contact 200 and its associated armature 204, the conductor I00, the line switch I03, the conductor I02, the bridge across the conductors of the line I00 at the calling substation A, the upper line conductor IN, the switch I03, the conductor I05, the armature 2M and its associated contact 202, the conductor I30, and through the upper winding of the relay 220 to battery. The line relay 220 operates in response to its energization over the above-traced circuit to complete, at its armature 22I and associated contact 222, a circuit extending from ground at the armature 200 and by way of the conductor I42 for energizing the slow-to-release hold relay 230.

The hold relay 230, upon operating, prepares, at its armature 23I and associated contact, a circuit, traced hereinafter, for energizing the upper winding of the polarized relay 200 when the minor switch H0 is operated to a position corresponding to an idle final selector switch in a selected group of such switches. At its armature 232 and associated contact 232, the hold relay 230 prepares a circuit for energizing the motor magnet 280 and a locking circuit for the slow-to-release relay 240. At its armature 236, the relay 230 applies ground to the control conductor I01, thereby to hold the line switch I03 operated and to complete a circuit extending by way of the closed oil-normal springs 243 for maintaining the slow-to-release relay 240 energized, it being understood that the last-mentioned relay operates immediately upon the seizure of the switch I04. At its armature 235, the relay 230 completes a circuit extending by way of the conductor I36 for energizing the lower winding of the polarized relay 200. This polarized relay is so constructed that it does not operate in response to the energization of its lower winding, but s conditioned by such energization to be exceedngly fast. acting when its upper winding is subsequently energized. The relay 240, when operated, prepares, at its armature I, a further point in the holding circuit for itself and for energizing the motor magnet 234. With the relays 220, 230 and 240 of the switch I04 operated, the control means included in this switch is conditioned to be responsive to the series of impulses comprising the first digit dialed at the calling substation A.

At the beginning of the first impulse of this digit, when the previously traced circuit for energizing the line relay 220 is interrupted at the impulsing device of the calling substation, this relay restores to complete, at its armature HI and associated contact 223, the above-noted circuit for holding the relay 240 operated during impulsing and for energizing the motor magnet 285 of the switching mechanism I30, this circuit extending from ground at the armature 200 by way of the restored armature HI and its associated contact 223, the operated armature 232 and its associated contact 233 to the operated armature 2 where it divides, one branch extending through the lower winding of the relay 240 to battery, and the other branch extending over the conductor HI, and through the closed oil-normal springs 239 and the winding of the magnet 205 to battery. This magnet, upon being energized over the above-traced circuit, immediately operates its armature to cause the carriage member I20 to be translated one step in a horizontal direction or to a position such that the respective wipers I23 to I 20, inclusive, st'od opposite the conductors comprising the first conductor set of the group of conductors in which they are included. Upon taking this first step, the oil-normal springs 240 and 241 are closed and the off-normal springs 243 are opened. While the operation of these springs to their respective off-normal positions is without eifect at this time, it is noted that closure of the springs 241 prepares a circuit for energizing the release magnet 215, closure of the springs 240 prepares a circuit for energizing the cut-in magnet 203, and opening of the off-normal springs 243 interrupts the original operating circuit for the slow-to-release relay 240. The last-mentioned relay is held operated, however, by virtue of its energization over the above-traced circuit extending from ground at the amature 200 and including its lower winding.

At the end of the first pulse of the first digit dialed, when the line relay 220 again operates, the previously-traced circuit for energizing the motor magnet 285 is interrupted at the armature 22I, thereby conditioning this magnet and its associated ratchet and pawl mechanism to step the wipers of the group including the set I23, I24 and I25 a second step. During each succeeding impulse of the series of impulses comprising the first digit, the line relay 220 alternately operates and restores to cause the motor magnet 20! to step the wipers I23 to I20, inclusive, horizontally at the rate of one step for each impulse received by the automatic switch. During such impulsing, the relays 230 and 240, by virtue of their slow-to-release characteristics, remain operated.

Since the outgoing line I3I terminates at a set of bank conductors corresponding to the second position of the wipers carried by the carriage member I20, the first digit dialed at the calling substation A will necessarily comprise two impulses, so that, at the. conclusion of this digit, the wipers I23 to I25, inclusive, stand in their respective second positions or opposite the bank conductors connected to the trunk line conductors I32, I33 and I34, respectively. Shortly following the end of the first digit and with the line relay in its operated position, such that the circuit for energizing the lower winding of the slow-to-release relay 240 is interrupted at the armature Hi, the last-mentioned relay restores to interrupt, at its armature 2, its holding circuit and the previously-traced circuit for energizing the motor magnet 285. At its armature 242, the relay 240 upon restoring completes a circuit for energizing the cut-in magnet 280, this circuit extending from ground on the armature 200 by way of the operated armature I and its associated contact 222, the conductor I42, the restored armature 242, the conductor I43, the closed off-normal springs 240, the oil-normal spring 248 and its associated contact 253, and through the winding of the magnet 205 to battery. This magnet upon operating its armature rotates the wipers in the group comprising the wiper set I23, I24 and I25 into engagement with their respective oppositely disposed bank conductors and their respective associated bus bars. It will be understood, in view of the foregoing description, that the carriage member I20 is held in its translated and rotated position by the armature associated with the release magnet 215. With the member I20 in the position noted, test circuits are prepared for determining the condition of the final selector switches in the selected group of switches.- Thus, the control conductor I34 included in the trunk line I3I leading to the switch I05 is connected by way oi! the wiper I25, the bus bar I22, and the conductor III to the fifth contact of the contact set II3 embodied in the minor switch IIO. Each of the test conductors included in the lines incoming to the remaining nine final selector switches of the selected group similarly extends by way of the remaining nine test wipers carried by the carriage member I20 to one of the remaining contacts of the set H3.

When the cut-in relay 295 operates, it actuates its oil-normal spring 248 to the oil-normal position thereby to interrupt, at the contact 250, its energizing circuit and to complete, at the contact 249, a circuit for energizing the motor magnet 255 of the minor switch I I0. This last-mentioned circuit extends from ground on the restored armature 208 by way of the operated armature HI and its associated contact 222, the conductor I42, the restored armature 242, the conductor I43, the closed off-normal springs 245, the oiT-normal spring 248 and its associated contact 248, the selfinterrupting contacts 255 associated with the armature of the magnet 255, and through the winding of this magnet to battery. By virtue of its energization over the above-traced circuit, the magnet 255 operates buzzer fashion and in cooperation with its associated ratchet and pawl mechanism, drives the wipers H4, H5 and H5 successively into engagement with the contacts of their respective associated contact sets I I I, I I2 and I I3. Upon the wipers noted taking their first step, the off-normal springs 245 are closed to prepare a circuit, held open at the armature 232 and associated contact 234, for energizing the release magnet 255.

It will be seen from a consideration of the final selector switch I05 that, if any particular final selector switch in the selected group is idle, battery is present on the control conductor incoming to the switch and corresponding to the conductor I34, whereas, if it is busy, ground is present on this conductor. Thus, when the switch I05 is idle, battery from the upper winding of the relay 320 is impressed through the oil-normal springs 381 on the conductor I34. If, on the other hand, this switch is busy, the armature 3| I of the hold relay 3" is operated so that ground is Impressed on the control conductor I34. With the various final selector switches of the selected group thus marked in the contacts of the contact level II3, the minor switch continues to operate until the wiper III engages the test conductor leading to an idle one of these switches. In the case under consideration wherein the switch I is assumed to be the first idle final selector switch of the selected group, ground is present on the first four contacts of the set II3 sothat the motor magnet 255 steps the wipers II4 to H6, inclusive, until they stand in engagement with their respective associated fifth contacts. When this occurs, a circuit is completed for energizing the upper winding of the polarized relay 200, this circuit extending from ground on the control conductor I01, through the winding noted, by way of the conductor I31, the operated armature 23I, the conductor I40, the wiper H8 and its associated fifth contact, the conductor II9, the bus bar I22, the wiper I25, the conductor I34, the off-normal springs 381, and through the upper winding of the relay 320 to battery. In response to the energi zation of its upper winding over the above-traced circuit, the polarized relay 200 immediately operates to interrupt, at its armature 208, the previously traced circuit for energizing the hold relay 230 and the motor magnet 255, whereby the wipers II4 to II 0, inclusive, are brought to rest in engagement with their respective associated fifth contacts. At its armature 208, the relay 200 completes an obvious holding circuit for maintaining its lower winding energized and, at its armature 201, it short-circuits its upper winding and applies ground to the control conductor I34 thereby to mark the seized final selector switch I05 as busy in the bank conductors of the other intermediate selector switches to which it is accessible. The application of ground to this conductor also results in the energization of the upper winding of the relay 320 causing this relay to operate. It is noted that the short-circuiting of the upper winding of the polarized relay 200 does not cause this relay to restore, since, when once operated, the lower winding thereof, if energized, maintains the relay in its operated position. At its armatures 20I and 204, the relay 200 upon operating interrupts the previously traced circuit for energizing the line relay 220 and connects the calling line through to the trunk line I3I incoming to the seized final selector switch I05. When the relay 220 restores following its de-energization, it interrupts, at its armature 22I and associated contact 222, a further point in the operating circuit for the hold relay 230 and, at this same armature and its associated contact 223, prepares a further point in the circuit for energizing the release magnets 255 and 215.

When the polarized relay 200 operates, a circuit is completed for energizing the line relay 300 included in the seized final selector switch I05, this circuit extending from ground at the upper winding of this relay by way of the conductor I82, the upper side of the loop to the calling substation, through the bridge across the line conductors at this substation, back over the lower side of this loop, the conductor I8I and through the lower winding oi the relay to battery. Upon operating, the line relay 300, at its armature Ni and the associated contact 302, completes an obvious circuit for energizing the slow-to-release hold relay 3I0. This last-mentioned relay, upon operating, applies, at its armature 3H, holding ground to the control conductor I34 and, at its armature 3I2 and associated contact 3I3, pre-' pares a circuit, traced hereinafter, for energizing the motor magnet 388 included in the minor switch I50. It will be noted that the ground applied to the control conductor I34 is extended back by way of the operated armature 201 of the polarized relay 200 to the control conductor I01 thereby to hold the selector switch I04 and the line switch I03 operated. Shortly following the operation of the hold relay 3I0 in the final selector switch I05, the hold relay 230 in the intermediate selector switch I04 restores, to remove, at its armature 236, multiple ground from the control conductor I0'I. At its armature 235, the hold relay 230, upon restoring, interrupts the original circuit for energizing the lower winding of the polarized relay 200 and, at its armature 232 and associated contact 234, it prepares a further point in the circuit for energizing the release magnets 265 and 215. At its armature 23I, the hold relay opens the short circuit across the upper winding of the polarized relay 200. With the system in this condition, it will be seen that the connection has been extended to the seized final selector switch I05 and that only the relay 200 of the switch I04 is operated. Before describing the sequence of operations which occur following the seizure of the final selector switch I05 and in or der to complete the description it will be assumed that all of the final selector switches in the group selected by the switch mechanism I30 are busy at the time the minor switch IIO starts to operate in search of an idle one thereof. With this condition prevailing each of the control conductors of the trunks leading to the respective switches of the selected group has ground thereon and, as a consequence, the wipers H4, H5 and IIS are rotated by the motor magnet 255 until they reach their respective eleventh positions at which time the oil-normal springs 23! and 244 are closed and the oil-normal springs 239 are opened. Closure of the springs 23! applies busy tone current to the loop extending to the calling partys substation to indicate to the party thereat that the desired connection cannot be completed. When the springs 244 close, a circuit is completed for energizing the upper winding of the slow-torelease relay 240, this circuit extending from ground at the armature 208 by way of the operated armature 22I and its associated contact 222, the conductor I42, the off-normal springs 244 and the upper winding noted to battery. With the off-normal springs 239 open the circuit for energizing the magnet 285 is interrupted to permit the proper release of the partially completed connection. The relay 240 upon being energized over the above-traced circuit operates to interrupt at its armature 242 the previously traced operating circuit for the motor magnet 255. At its armature I, the relay 240 prepares the previously mentioned circuit for energizing the lower winding of the relay 240, this circuit being held open at the operated armature 22I of the line relay 220. Busy tone is continuously transmitted to the calling party until he clears out the partially completed connection to interrupt the circuit holding the line relay 220 energized. When this relay falls back it interrupts, at the armature 22I and associated contact 222, the operating circuit for the hold relay 230 and the circuit including the upper winding of the relay 240. At this same armature and the associated contact 223, the relay 220 momentarily completes a circuit for energizing the lower winding of the relay 240, which circuit is interrupted when the hold relay 230 f'lls back. It is pointed out that the provision oi the now open oil-normal springs 238 prevents the magnet 285 from being energized during the period required for the restoration of the hold relay 230 and, thus, prevents this magnet from attempting to pull the wipers mounted on the carriage member I20 and respectively engaged with the conductors of a group of conductors in the conductor bank oi the switch mechanism I30. Shortly following the restoration of the relay 220 the hold relay 280 falls back to interrupt at its armature 282 and associated contact 233 the above noted circuit for energizing the lower winding of the relay 240 and to complete at this same armature and its associated contact 234 circuits for energizing the release magnets 285 and 215, these circuits both starting at ground on the armature 200 and extending by way of the armatures HI and 282 to the conductor I44 where they divide, one extending by way of the oil-normal springs 245 and the winding of the magnet 255 to battery and the other extending by way of the off-normal springs 24! and the winding of the relay 215 to battery. These magnets upon being energized permit the spring-biased wiper carriage members 01 the respective switch mechanisms I I0 and I30 to restore the wipers thereof to their respective normal positions at which time the various pairs of off-normal springs shown are returned to their normal positions. The hold relay 230 upon falling back also interrupts, at its armature 235, the circuit for energizing the lower winding of the polarized relay 200 and removes, at its armature 235, ground from the control conductor I01. This last-mentioned operation permits the line switch I08 to restore to its normal idle condition. Thus, the partially completed connection is released.

Continuing now with the sequence oi operations which occur following the seizure of the final selector switch I05, it will be seen that with the line relay 300, the hold relay 3 I 0, and the slow-torelease relay 320 operated, the switch is conditioned to be responsive to impulses comprising the two final digits dialed at the calling substation A. At the beginning of the first impulse of the second digit, the line relay 300 restores to complete, at its armature 30I and associated contact 808, the above mentioned circuit for energizing the motor magnet 388, this circuit extending from ground at the armature MI, by way or the con tact 303, the operated armature 3I2, the contact 3I3, the operated armature 32I, the contact 322, the conductor I84, and through the winding of the magnet 380 to battery. The energization of the magnet 388 causes the associated ratchet and pawl mechanism to step the wipers I54 to I58, inclusive, from their respective normal positions to their respective first off-normal positions or into engagement with the respective first contacts of the contact sets I5I, I52 and I53. At the conclusion of the first pulse, when the line relay 300 reoperates to cause the deenergization of the magnet 388, this magnet, in conjunction with its ratchet and pawl mechanism, is conditioned to drive the wipers I54 and I56 to their respective second oil-normal positions. Upon the switch taking its first step, the off-normal springs 380 are closed to prepare a circuit for energizing the release magnet 389, and the cit-normal springs 391 are opened to interrupt the circuit over which the relay 320 was originally energized. The motor magnet 399 is alternately energized and deenergized, in accordance with the impulses oi the second digit, to step the wipers IN to I58,inclusive, over the contacts of their respective associated contact sets at the rate of one contact for each impulse. In the case under consideration wherein the called line I10 terminates at a conductor set in the group of bank conductors comprising the smaller groups respectively associated with the wipers I15, I16 and I11, the second digit will necessarily comprise five impulses so that, at the conclusion of the digit, the wipers I 54, I55 and I 56 stand in engagement with their respective associated fifth contacts. It will be understood that the relays 3I0 and 320 due to their slow-torelease characteristics remain operated during such impulsing.

At the conclusion of the second digit, the line relay 300 remains energized for a suflicient period of time to permit the slow-to-release relay 320 to restore. When this occurs, the housing circuit for the relay 320 and the previously traced circuit for energizing the motor magnet 388 are interrupted at the armature 32I and its associated contact 322, Simultaneously, a circuit is prepared, at this same armature and its associated contact 323, for energizing the motor magnet 390 included in the switch mechanism E65. Thus, the final selector switch W5 is conditioned to be responsive to the impulses comprising the third or units digit dialed at the calling subscribers substation A.

At the beginning of the first impulse of the third digit, when the line relay 300 again restores, the above-noted circuit for energizing the motor magnet 390 is completed, this circuit ex-r tending from ground at the armature 30I by way of the contact 303, the armature 3I2, the contact :3, the now restored armature 32i and its associated contact 323, the conductor I96, the restored armature 355, the conductor I95, the restored armature 381, the conductor I81, and through the winding of the magnet 390 to battery. This magnet in conjunction with its associated ratchet and pawl mechanism translates the carriage member I15 horizontally to step the group of wipers comprising the wiper set I15, I16, I11 one step or to positions opposite the respective first bank conductors of their respective associated subgroups of bank conductors. the alternate energization and deenergization of the motor magnet 390 in accordance with the impulses comprising the third digit, the wipers noted are stepped at the rate of one step for each impulse. In the present instance, wherein the conductors of the line I10 terminate at the bank conductors corresponding to the first off-normal position of the wipers I15 to I11, inclusive, the third digit will necessarily comprise only one impulse so that, at the conclusion thereof, the wipers I15 to I11, inclusive, stand opposite the respective first bank conductors of their respective associated bank conductor subgroups. Simultaneously with the energization of the motor magnet 390 at the beginning of the first impulse of the third digit, a circuit is completed for energizing the slow-to-release relay 360, this circuit extending from ground on the restored armature 30I by way of the contact 303, the operated armature 3I2 and its associated contact 3 I 3, the restored armature 32I and its associated contact 323, the conductor I94, the restored armature 355, the conductor I95, the restored armature 381, the conductor I81, and through the winding of the re- Due to I lay 300 to battery. This relay, upon operating at its armature I and associated contact 382, prepares a circuit for energizing the slow-to-release relay 310 and, at this same armature and its associated contact 303, interrupts a point in the circuit for energizing the cut-in magnet 392. The above-noted circuit for energizing the slowto-release relay 310 is completed upon the carriage member I15 being translated one step horizontally, thereby to close the oil-normal springs 393. This circuit extends from ground at the springs noted, by way of the conductor I92, the armature 36! and its associated contact 362, and through the winding of the relay 310 to battery. It is noted that simultaneously with the closure of the oft-normal springs 393, the oil-normal springs 390 are closed to prepare a circuit for energizing, the release magnet 39L The relay 310 upon operating opens, at its armature 31I and associated contact 312, a point in the circuit, traced hereinafter, for energizing the lower winding of the relay 380 and, at this same armature and its associated armature 31d, prepares a circuit, traced hereinafter, for energizing the busy relay 350.

At the conclusion of the third digit, the line relay 330 remains operated so that the abovetraced operating circuit for the slow-to-release relay 385 is interrupted at the armature 39! and its associated contact 3%. The last-mentioned relay restores after an interval, to complete the above-mentioned circuit for energizing the cutin magnet 392 and to interrupt the above-traced circuit holding the slow-to-release relay 31d operated. The circuit for energizing the cut-in magnet 382 extends from ground at the on?- normal springs 393, by way of the conductor I52, the restored armature 36E, the contact 363,

, the conductor 593, the closed off-normal springs 393, and through the winding of the magnet 392 to battery. This magnet, upon being energized, operates its armature to rotate the wipers carried by the carriage member I15 into engagement with their respective oppositely standing bani: conductors and their respective associated bus bars. Thus, the wipers I15, 516 and Ill are brought into engagement with the bars I18, I19 and I80, respectively, and the bank conductors to which are connected the conductors I12, I13 and I14, respectively, of the called line I10. When the cut in magnet 392 operates its armature, the oiT-normal springs 394 are opened to interrupt the energizing circuit for this magnet, the carriage member I15 being held in its translated. and rotated position by the release magnet 3!".

The sequence of operations which occur following the seizure of the called line by the final selector switch 105 depend upon whether this line is found idle or busy. Thus, at the time the called line I10 is seized by the switch and following the operation oi the cut-in magnet 392, the slowtorelease relay 310 remains operated so that a circuit is prepared at the armatures 3H and 314 for energizing the busy relay 350. If the called line I10 is busy, ground is presenton the control conductor I14, whereas, if the called line is idle, battery is present on this conductor. Hence, if the line I10 is busy at the time it is seized, the above-noted circuit for energizing the relay 350 is completed, this circuit extending from ground on the conductor I14, by way of the wiper I11, the bus bar I80, the conductor I53, the wiper I56 and its associated fifth contact, the

, conductor I60, the armature 385, the contact 386, the armatures 3H and 314, the conductor I86, and through the winding of the busy relay 350 to battery. This relay, upon operating, interrupts, at its armature 352 and associated contact 353, a further point in the circuit for energizing the lower winding of the relay 380 and, at this same armature and its associated contact 35$, prepares an alternative circuit for maintaining itself operated when the slow-to-release relay 319 restores. The alternative circuit noted extends from ground on the control conductor by way of the operated armature 352 and its associated contact 354, the conductor i9l, the contact the armature 314, the conductor and through the winding of the busy relay to battery. The busy relay upon operating also applies, at its armature 35L busy tone current to the loop extending through the operated se l-ector switch i3 3 and the operated line switch to the receiver at the calling subscribers substation indicate the calling party thereat the busy condition of the called line.

When this occurs, the calling party may, by hanging up, interrupt the loop holding the line relay aerated, thereby to cause the hold relay to r store. This latter relay, upon restoring its armature l, removes ground from the control The recon uctors le moval of ground from the conductor permits the busy relay to restore. When the hold relay 33D falls back, it also completes, at its armature 352 associated contact 35%, the previously mentioned circuit extending from ground at the armature by way the conductor energizing the release magnets and 39%. These magnets, upon operating their respective armatures, cause the minor switch ltd and the switching mechanism 165 to be restored to normal. With these switches restored to normal, the various off-normal springs shown are returned to their respective normal positions. The removal of ground from the control conductor it]? permits the line switch 103 to restore to normal and interrupts the circuit holding the polarized relay 200 energized. As a consequence, this relay restores to complete, at its armature 208, the above-noted circuit for energizing the release magnets 265 and 215, which magnets in turn operate to cause the minor switch lid and the switch mechanism 130 to be restored to normal. Thus, the switch train leading to the called subscribers line is released.

In the event the called line 510 is idle at the time it is seized by the final selector switch I05, battery from a relay in the line switch associated with the called line is present on the control conductor I14 and, consequently, the busy relay 350 is not energized over the above-traced circuit. Shortly after the seizure of the line and when the relay 310 restores, a circuit is completed for energizing the lower winding of the relay 380, this circuit extending from battery on the control conductor I14 by way of the wiper I11, the bus bar I80, the conductor I63, the wiper I58 and its associated fifth contact, the conductor I60, the armature 385 and its associated contact 386, the armature 3H and its associated contact 312, the conductor 188, the lower winding of the relay 380, the conductor I83, the contact 353, and the armature 352 to ground on the control conductor i34. The relay 380 operates, upon the energization of its lower winding, to complete, at its armature 381 an obvious locking circuit for itself extending from ground on the control conductor I34 and through its upper winding to battery. At its armature 301, the relay 30! opens a further point in the previously traced circuit for energizing the slow-to-release relay 300 and the motor magnet 330. At its armatures 304 and 305, the relay 330 extends ground from the control conductor I34 to the bank conductor engaged by the wiper I11, thereby to mark the called line I10 as busy and prevent its seizure by another final selector switch until the established connection is released. At its armature 383, the relay 380 completes a path for applying ring-back tone current to the loop extending to the calling subscriber and, at its armatures I and 382, it connects the trunk conductors I41 and I48 to the conductors I51 and I58, respectively, thereby to apply ringing current to the loop extending to the called subscribers substation 3. The path of this current extends from the ringing current generator at the contact 342 by way of the armature 3, the conductor I41, the armature 38!, the conductor I51, the wiper 54 and its associated fifth contact, the conductor IN, the bus bar 118, the wiper iii, the conductor 512, the signal device bridged across the line conductors I12 and H3 at the called substation, the line conductor iii, the wiper I10, the bus bar 18, the conductor V52, the wiper I55 and its associated fifth contact, the conductor .58, the operated armature 332, the conductor 148, the armature 343 and its associated contact 345, the conductor 1'85, and through the lower winding of the rin cut-off relay 530 to the opposite side of the ringing current generator. A portion of this current is by-passed through the receiver at the calling partys substation by way of the condenser I49, the lower side of the loop including the trunk conductor N3, the receiver at the calling partys substation, the upper side of the loop including the conductor I32, through the left-hand winding of the impedance 398 to the grounded side of the ringing current generator. It is noted that the ring cut-oil relay 340 is so constructed that it does not operate in response to the energization of its lower winding by the alternating ringing current.

When the called party answers, a direct current path is bridged across the line conductors I12 and I13 at the called substation, thereby to complete a direct current circuit for energizing the lower winding of the ring cut-of! relay 340, which circuit is identical with that traced above and traversed by the ringing current, and extends from ground at the contact 342 to battery at the lower terminal of the lower winding of the relay 340. In response to the energization of its lower winding, the relay 340 partially operates to complete the X contacts associated with its armature 341, thereby to cause the energization of its upper winding over an obvious circuit. When this upper winding is energized, the relay 340 fully operates to interrupt, at its armatures 3H and 344 and their respective associated contacts 342 and 345, the application ringing current and ring-back tone current to the loops extending respectively to the called and calling subscribers substations. At these last-mentioned armatures and their respective associated contacts 343 and 345, the calling line is connected to the called line so that a conversational circuit is completed-between the calling telephone A and the called telephone B. It is pointed out that talking battery is supplied to the loop extending to the called subscriber's substation through the windings of the impedance element 338, which windings are connected in series with the exchange battery across the conductors I45 and I46. Similarly, talking battery is supplied to the talking loop extending to the calling subscribers substation through the windings of the line relay 300. The system remains in this condition until the connection is cleared out at the calling subscriber's substation.

If the called party hangs up first, nothing oc curs, the entire switch train being held operated by virtue of the fact that the line relay 300 is maintained energized over the closed loop extending to the calling substation, and the hold relay (H0 is held operated by the line relay 300 thereby to maintain ground on the control conductor I34 at the armature 3i I. When, however, the calling party hangs up his receiver to interrupt the circuit holding the line relay 300 energized, this relay restores, to open the operating circuit for the hold relay 3"). The hold relay, upon restoring its armature 3i I, removes ground from the control conductors I0! and I34 thereby to cause the restoration of the line switch I03, the polarized relay 200 in the intermediate selector switch I0 5 and the relays 340 and 380 in the final selector switch I05. When the relay 200 restores it completes the above-mentioned circuit for energizing the release magnets 205 and 215, thereby to return the switch I04 to its normal idle condition. The hold relay Elli upon restoring its armature 3I2, completes a circuit extending by way of the conductor m3 for energizing the release magnets 380 and 3%. These magnets upon operating permit, respectively, the minor switch N30 and the switch mechanism I65 to restore to normal. Thus the switch train is re" stored to the condition which prevailed before the above described connection was established and the switches involved therein are ready for further use.

From the foregoing description it will be apparent that each of the automatic switches included in each switching unit comprises a bank of conductors common to all of the switches in the unit and adapted to serve both as wiper contacts for all of the switches and as multiple conductors between the switches, a group or wipers associated with the bank conductors and means for selectively moving the group of wipers into engagement with different groups of the bank conductors. More specifically, the intermediate selector switch I04, for example, at which the incoming trunk line I04 terminates, comprises means included therein and comprising the switching mechanism I30 for selectively associating the line I04 with a selected group of the outgoing lines including the trunk line I3I leading to the final selector switch I 05, and means including the minor switch 0 and the polarized relay 200 for connecting the incoming line I04 to a selected line, such, for example, as the line" I3I, in the group of outgoing lines. In the unit including the final selector switch I05, on the other hand, the means for associating the line I3I incoming thereto with a selected group of the subscribers lines comprises the minor switch I50 and the means for connecting the line I3I to a particular line, such, for example, as the line I10, in a selected group of subscribers lines comprises the switching mechanism I65. Also, in the final selector switch I05 both the line group selecting means and the line units selecting means are responsive to operation of impulse responsive means comprising the line relay 300, whereas in the intermediate selector switch I04 only the group selecting means is responsive to the impulse responsive line relay 220, the line unit selecting means operating automatically to select a particular line leading to an idle final selector switch immediately following the line group selection.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is contemplated to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

We claim:

1. In a signalling system, a plurality of groups of outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively connecting different ones of said incoming lines to difierent' ones of said outgoing lines, said switching unit comprising a bank of conductors and a plurality of groups of wipers, said bank conductors being common to all of said switches and adapted to serve both as wiper contacts for all or" said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein, each of said groups of wipers being included in a corresponding one of said switches, and means for selectively moving the wipers of each of said groups of wipers into engagement with the difierent conductors-in the groups of said bani: conductors.

2. In a signalling system, a plurality of groups of outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively and simultaneously connecting diiferent ones of said incoming lines to different ones of said outgoing lines, said switching unit comprising a bank of conductors common to all of said switches and adapted to serve both as wiper contacts for all of said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, each of said incoming lines terminating at a different one of said switches, means included in each switch for selectively associating the line incoming thereto with a selected group of said outgoing lines, and means included in each switch for connecting the line incoming thereto to a particular line in a selected group of said outgoing lines, each of the means of one of said two lastnamed means comprising a group oi wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein.

3. In a signalling system, a plurality of groups of outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively and simultaneously connecting different ones of sa d incoming lines to different ones of said outgoing lines, said switching unit comprising a bank of conductors common to all of said switches and adapted to serve both as wiper contacts for all of said switches and as multiple conductors between said switches, said bank conductors being arranged in a. plurality of groups individually corresponding to said groups of outgoing lines, each of said incoming lines terminating at a different one of said switches, impulse responsive means included in each of said switches, means included in each switch and responsive to the operation of the impulse responsive means thereof for selectively associating the line incoming thereto with a selected group or said outgoing lines, and means included in each switch for connecting the line incoming thereto to a particular line in a selected group of said outgoing lines, each of the means of one of said two last-named means comprising a group of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein.

4. In a signalling system, a plurality of groups of outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively and simultaneously connecting different ones of said incoming lines to different ones of said outgoing lines, said switching unit comprising a of conductors common to all of said switches and adapted to serve both as wiper contacts for all or said switches as multiple conductors oetween said switches, said bank conductors "'1' arranged in a plurality of groups individually corresponding to said groups oi outgoing lines, each of said incoming lines terminating at a dif ferent one of said switches, impulse responsive means included in each of said switches, means included in each switch and responsive to the operation of the impulse responsive means there of for selectively associating the line incoming thereto with a selected group of said outgoing lines, and means included in each switch and antomatically operable immediately following the selection of a group of said outgoing lines for connecting the line incoming thereto to a partlcular lines in the selected group, each of the means of one of said two last-named means comprising a group 'of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein.

5. in a signalling system, a plurality of groups of outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively and simultaneously connecting difierent ones of said incoming lines to different ones of said outgoing lines, said switching unit comprising a bank of conductors common to all or said switches and adapted to serve both as wiper contacts for all of said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, each of said incoming lines terminating at a different one of said switches, impulse responsive means included in each of said switches, means included in each switch and responsive to the operation of the impulse responsive means thereof for selectively associating the line incoming thereto with a selected group of said outgoing lines, and means including each switch and responsive to the operation of the impulse responsive means thereof for connecting the line incoming thereto to a particular line in a selected group of lines, each of the means of one of said two last-named means comprising a group of wipers including at least one wiper individual to each or the groups of said bank conductors and adapted to engage a conductor therein.

6. In a signalling system, a plurality of groups or outgoing lines, a plurality of incoming lines, and an automatic switching unit comprising a plurality of automatic switches for selectively and simultaneously connecting diflerent ones of said incoming lines to diflerent ones of said outgoing lines, said switching unit comprising a bank of conductors common to all of said switches and adapted to serve both as wiper contacts for all of said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, each of said incoming lines terminating at a diflerent one of said switches, means included in each switch for selectively associating the line incoming thereto with a selected group of incoming lines, means included in each of said switches for selecting a particular line in a selected group of lines, each of the means of said two last-named means comprising a group of wipers including at least one wiper individual to each of the groups or said bank conductors and adapted to engage a conductor therein, and means included in each switch for connecting the line incoming thereto to a selected outgoing line only in the event said selected line is idle.

7. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each 01' said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, means included in each of said switches for associating the one line incoming thereto with a predetermined wiper of the switching mechanism thereof, and means included in each switch for operating the predetermined wiper thereof into engagement with a predetermined conductor in the group of said bank conductors individual to the predetermined wiper, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

8. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, means comprising a stepping switch included in each of said switches for associating the one line incoming thereto with a individual to the predetermined wiper, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

9. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, means included in each of said switches for associating the one line incoming thereto with a predetermined wiper of the switching mechanism thereof, impulse responsive means included in each of said switches, and means included in each of said switches and responsive to the operation of the impulse responsive means thereof for operating the predetermined wiper thereof into engagement with a predetermined conductor in the group of said bank conductors individual to the predetermined wiper, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

10. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, impulse responsive means included in each of said switches, means included in each of said switches and responsive to the operation of the impulse responsive means thereof for associating the one line incoming thereto with a predetermined wiper of the switching mechanism thereof, and means included in each of said switches and responsive to the operation of the impulse responsive means thereof for operating the predetermined wiper thereof into engagement with a predetermined conductor in the group of said bank conductors individual to the predetermined wiper, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

11. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each' of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank a conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, a stepping switch included in each of said switches, impulse responsive means included in each of said switches, means included in each of said switches and responsive to the operation of the impulse responsive means thereof for causing the stepping switch thereof to associate the one line incoming thereto with a predetermined wiper of the switching mechanism thereof, and means included in each of said switches and responsive to the operation of the impulse responsive means thereof for operating the predetermined wiper thereof into engagement with a predetermined conductor in the group of said bank conductors individual to the predetermined wiper, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

12. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually cororesponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, a bus bar associated with each of said wipers,

means included in each of said switches for ased line in a selected group of said outgoing lines.

13. In a signalling system, an automatic switching unit including a plurality of automatic switches, a plurality of groups of lines outgoing from said unit, a line incoming to each of said switches, said unit comprising bank conductors adapted to serve both as wiper contacts for said switches and as multiple conductors between said switches, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of outgoing lines, a plurality of groups of wipers associated with said bank conductors, each of said groups of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein and comprising in combination with said bank conductors a switching mechanism embodied in one of said switches, a bus bar associated with each of said wipers, means included in each switch and comprising a stepping switch having bank contacts connected to the bus bars of the switch in which it is included for associating the one line incoming thereto with a predetermined wiper of the switching mechanism thereof, and means included in each switch for operating the predetermined wiper thereof into engagement with a predetermined conductor in the group of said bank conductors individual to the predetermined wiper and into engagement with the associated bus bar, whereby any one of said incoming lines may be connected to a selected line in a selected group of said outgoing lines.

14. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to the lines outgoing from said unit; a plurality of groups of wipers each including a wiper individual to each smaller group of said bank conductors, the wipers of each group being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit; and means individually associated with each of said groups of wipers for simultaneously moving the wipers of the corresponding group to any one of said positions and for thereafter moving the same into engagement with the respective oppositely disposed conductors.

15. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups, all of said bank conductors being disposed in the same plane in substantially parallel relation and being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to the lines outgoing from said unit, a plurality of groups of wipers each including a wiper individual to each smaller group of said bank conductors, the wipers of each group being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, and means individually associated with each of said groups of wipers for simultaneously moving the wipers of the corresponding group to any one of said positions and for thereafter moving the same into engagement with the respective oppositely disposed conductors.

16. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups, all of said bank conductors being disposed in the same plane in substantially parallel relation with substantially the same spacing between the conductors in each smaller group and substantially the same spacing between the adjacent conductors in each adjacent pair of smaller groups, whereby the corresponding conductors of the smaller groups in each group of said bank conductors form conductor sets adapted to be connected to lines outgoing from said unit, a plurality of groups of wipers each including a wiper individual to each smaller group of said bank conductors, the wipers of each group being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, and means individually associated with each of said groups of wipers for simultaneously moving the wipers of the corresponding group to any one of said positions and for thereafter moving the same into engagement with the respective oppositely disposed conductors.

17. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups,' said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said unit, a plurality of carriage members, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on each of said carriage members, the wipers of each group being so arranged relative to said bank conductors that when the associated carriage member is moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, and

means individually associated with each of said carriage members for moving the corresponding member in one direction to any one of said positions and for thereafter moving the same in another direction to bring the wipers carried thereby into engagement with the respective oppositely disposed conductors.

18. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said unit, a plurality of carriage members, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on each of said carriage members, the wipers of each group being so arranged relative to said bank conductors that when the associated carriage member is moved to any one of a number of pfidetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors,

whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, means individually associated with each of said carriage members for translating the same to any one of said positions, and means individually associated with each of said carriage members for rotating the corresponding carriage member to bring the wipers carried thereby into engagement'with the respective oppositely disposed conductors following the translation of the corresponding carriage member to any one of said positions.

19. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number oi smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in,

each group form conductor sets adapted to be connected to lines outgoing from said unit, a plurality of carriage members, a group of wipers including a wiper individual to each smaller group ot'said bank conductors mounted on each of said carriage members, the wipers of each group being so arranged relative to said bank conductors that when the associated carriage member is moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, means individually associated with each of said carriage members for translating the same to any one of said positions, means individually associated with each of said carriage members for rotating the corresponding carriage member to bring the wipers carried thereby into engagement with the respective oppositely disposed conductors following the translation of the corresponding carriage member to any one of said positions, and means individually associated with each of said carriage members for maintaining the corresponding carriage member in its translated and rotated position independently of said two last-named means.

20. An automatic switching unit including a plurality of automatic switches and comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being disposed in the same plane and so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a plurality of carriage members, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on each of said carriage members, the wipers of each group beingso arranged relative to said bank conductors that when the associated carriage member is moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said unit, means individually associated with each of said carriage members for translating the same to any one of said positions, means individually associated with each of said carriage members for rotating the correspondingf carriage member to bring the wipers carried thereby into engagement with the respective oppositely disposed conductors following the translation of the corresponding carriage member to any one of said positions, and means individually associated with each or said carriage members for maintaining the corresponding carriage member in its translated and rotated position independently of said two last-named means.

21. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank con-' ductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a group of wipers including a wiper individual to each smaller group of said bank conductors, said wipers being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, and means for simultaneously moving said wipers to any one of said positions and for thereafter moving said wipers into engagement with the respective oppositely disposed conductors.

22. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being disposed in the salne plane in substantially parallel relation and so arranged that the corresponding conductors in the smaller groups in each group form contact sets adapted to be connected to lines outgoing from said switch, a group of wipers including a wiper indi-- vidual to each smaller group of said bank conductors, said wipers being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the-smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, and means for simultaneously moving said wipers to any one of said positions and for thereafter moving said wipers into engagement with the respectively oppositely disposed conductors.

23. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, all of said bank conductors being disposed in the same plane in substantially parallel relation with substantially the same spacing between the conductors in each smaller group and being so arranged that the corresponding conductors in the smaller groups of each group form contact sets adapted to be connected to lines outgoing from said switch, a group of wipers including a wiper individual to each smaller group of said bank conductors, said wipers being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, and means for simultaneously moving said wipers to any one of said positions and for thereafter moving said wipers into engagement with the respective oppositely disposed conductors.

24. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, all of said bank conductors being disposed in the same plane in substantially parallel relation with substantially the same spacing between the conductors in each smaller group and substantially the same spacing between the adjacent conductors in each adjacent pair of smaller groups and being so arranged that the corresponding conductors in the smaller groups in each group form contact sets adapted to be connected to lines outgoing from said switch, a group of wipers including a wiper individual to each smaller group of said bank conductors, said wipers being so arranged relative to said bank conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, and means for simultaneously moving said wipers to any one of said positions and for thereafter moving said wipers into engagement with the respective oppositely disposed conductors.

25. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a group of wipers including a wiper individual to each smaller group of said bank conductors, said wipers being so arranged relative to said conductors that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, means for simultaneously moving said wipers to any one of said positions, and means for thereafter moving said wipers into engagement with the respective oppositely disposed conductors corresponding to said one position.

26. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductors sets adapted to be connected to lines outgoing from said switch, a carriage member, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on said carriage member, said wipers being so arranged relative to said bank conductors that when said carriage member is moved to any one of a number of predetermined posi- 'tions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, means for moving said carriage member in one direction to one of said positions, and means for thereafter moving said carriage member to bring said wipers into engagement with the respective oppositely disposed conductors corresponding to said one position.

27. An automatic switch comprising a-bank oi conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conducto sets adapted to be connected to lines outgoing from said switch, a carriage member, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on said carriage member, said wipers being so arranged relative to said bank conductors that when said carriage member is moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group comprise wiper sets adapted to be connected to a line incoming to said switch, means for translating said carriage member in one direction to one of said positions, and means for thereafter rotating said carriage member to bring said wipers into engagement with the respective oppositely disposed conductors corresponding to said one position.

28. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a carriage member, a group of wipers including a wiper individual to each smaller group or said bank conductors mounted on said carriage member, said wipers being so arranged relative to said bank conductors that when said carriage member is moved to any one of a number of predetermined positions the wipers stand opposite corresponding bank conductors in the smaller groups in each group of said bank conductors, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group oi said bank conductors comprise wiper sets adapted to be connected to a line incoming to said switch, means for translating said carriage member step by step in one direction to one of said positions, and means for thereafter moving said carriage mem-. ber to bring said wipers into engagement with the respective oppositely disposed conductors corresponding to said position.

29. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a number of bus bars, individual ones of said bars being associated with individual ones of the smaller groups 01 said bank conductors, a group of wipers including a wiper individual to each smaller group of said bank conductors, said wipers being so arranged relative to said conductors and said bus bars that when moved to any one of a number of predetermined positions the wipers stand opposite corresponding conductors in the smaller groups in each group of said bank conductors, and one oi said bus bars, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected by way of the associated bus bars to a line incoming to said switch, and means for simultaneously moving said wipers to any one of said positions and for thereafter moving said wipers into engagement with the respective oppositely disposed conductors and the respective associated bus bars.

30. An automatic switch comprising a bank of conductors arranged in groups each including a number of smaller groups, said bank conductors being so arranged that the corresponding conductors in the smaller groups in each group form conductor sets adapted to be connected to lines outgoing from said switch, a group of bus bars, individual ones of said bus bars being associated with individual ones of said smaller groups of said bank conductors, a carriage member, a group of wipers including a wiper individual to each smaller group of said bank conductors mounted on said carriage member, said wipers being so arranged relative to said bank conductors and said bus bars that when said carriage member is moved to any one of a number of predetermined positions the wipers carried thereby stand opposite corresponding conductors in the smaller groups in each group of said bank conductors and one of said bus bars, whereby the wipers standing opposite the corresponding conductors in the smaller groups in each group of said bank conductors comprise wiper sets adapted to be connected by way of the associated bus bars to a line incoming to said switch, means for translating said carriage to one of said positions, and means for thereafter moving said carriage to bring the wipers carried thereby into engagement with the respective oppositely disposed conductors corresponding to said one position and into engagement with the respective associated bus bars.

31. In a signalling system, a group of switches, an incoming line to each switch and a plurality of groups of outgoing lines accessible to all switches in the group, means included in each of said switches for selectively associating the line incoming thereto with a selected group of said outgoing lines, and means included in each of said switches for connecting the line incoming thereto to a particular line in a selected group of said outgoing lines, one of said two last-mentioned means of each switch comprising a bank of conductors and a group of wipers, said bank conductors being so connected and arranged as to serve both as wiper contacts for the wipers embodied in each of the switches of said group and as multiple conductors between the switches of said group, said bank conductors being arranged in a plurality of groups individually corresponding to said groups of. outgoing lines, said group of wipers including at least one wiper individual to each of the groups of said bank conductors and adapted to engage a conductor therein.

CLARENCE ERNEST LOMAX. JOHN H. VOSS. 

